<template>
    <div>
            <router-link
            tag="div"
            to="/"
            class="header-abs"
            v-show="showAbs">
                 <div class="iconfont header-abs-back">&#xe624;</div>
            </router-link>
            <div 
            class="header-fixed" 
            v-show="!showAbs"
            :style="opacityStyle"
            >
                <router-link to="/">
                     <div class="iconfont header-fixed-back">&#xe624;</div>
                </router-link>
                景点详情
            </div>
    </div>
</template>
 
<script>
export default {
    name:'DetailHeader',

    data(){
        return{
            showAbs:true,
            opacityStyle: {
                opacity: 0
            }
        };
    },
    methods:{
        handleScroll(){
            const top = document.documentElement.scrollTop
            if (top > 60) {
                let opacity = top / 140
                opacity = opacity > 1 ? 1 : opacity
                this.opacityStyle = { opacity }
                this.showAbs = false
            } else {
                this.showAbs = true
            }
        }
    },
    activated(){
        window.addEventListener('scroll',this.handleScroll)
    },
    unmounted () {
    window.removeEventListener('scroll', this.handleScroll)
    }

}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl'
  .header-abs
    position: absolute
    left: .2rem
    top: .2rem
    width: .8rem
    height: .8rem
    line-height: .8rem
    border-radius: .4rem
    text-align: center
    background: rgba(0, 0, 0, .8)
    .header-abs-back
      color: #fff
      font-size: .4rem
  .header-fixed
    z-index: 2
    position: fixed
    top: 0
    left: 0
    right: 0
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #fff
</style>
